1. Field of the Invention
The present invention relates to microwave ovens and more particularly, to a microwave oven protective circuit arrangement, which automatically cuts off power supply from the power supply unit to the microwave oven when detected a leakage of the microwave produced by the microwave oven.
2. Description of the Related Art
Following fast development of technology, a variety of high-tech produces have been developed to serve people and to improve our living conditions. In early days, cooking food is achieved by means of making a fire to heat food in a pot, pan, or the like. This cooking method requires much time to cook food. Further, the center part of the food may be not well cooked when the outer part of the food is overroasted. In order to eliminate this problem, microwave ovens are developed. A microwave oven is a kitchen appliance that cooks food by passing an electromagnetic wave through it, and heat is produced by the absorption of microwave energy by the water molecules in the food. The microwave energy produced by a microwave oven is about within 600 W˜2000 W that causes water molecules to oscillate at about 24.5 GHz. Therefore, heat produced by the absorption of microwave energy by the water molecules in the food enables the food to be thoroughly cooked within a short time.
A microwave oven can cook food quickly. However, a leakage of the microwave produced by a microwave oven may cause certain cumulative hazards and non-cumulative hazards to the user. It has been well acknowledged by scientists that a leakage of the microwave produced by a microwave oven will cause the following non-cumulative hazards.
1. Hazard to the Eyes
The eyes contain much amount of water. When the water molecules in the eyes absorb a microwave energy from a microwave oven, the limited flow rate of blood in the systems (cornea, lens, etc. of the eyes) cannot quickly carry the produced heat away from the eyes, and the heat energy may cause a severe damage to the eyes.
2. Hazard to the Genetic Organs
When the water molecules in the reproductive organ more particularly the testicle of a male absorb the microwave energy of a microwave oven, the heat thus produced may obstruct the testicle from generating sperm, resulting in infertility of the victim.
3. Hazard to the Skin and Subcutaneous Tissue
Because a microwave can pass through an insulative object, the skin and the subcutaneous tissue may be burned when radiated by the microwave produced by a microwave oven.
FIG. 4 illustrates the outer appearance of a conventional microwave oven. As illustrated, the microwave oven A comprises a housing A1, which defines a heating chamber A11, and a door A2 pivotally coupled to the housing A1 and adapted to close the heating chamber A11. The door A2 comprises a doorframe A21 and a window A22 at the center of the doorframe A21. When cooking, the food is put in the heating chamber A11, and then the door A2 is closed, keeping the heating chamber A11 in an enclosed status. During heating, the user can see the cooking status of the food through the window A22.
In order to isolate the microwave produced by a microwave oven, the door of the microwave oven must be specially designed. Normally, the door of a microwave oven is designed to have a protective metal net, a rubber that carries oxygen, a door sealing system, and a door locking system. According to actual practice, the microwave produced by a microwave oven may leak out of the microwave oven through the gaps in between the housing and the door and the gaps in between the doorframe and the window. After a long use of a microwave oven, the door of the microwave oven may wear mechanically, and gaps may be produced in between the door and the housing. Further, vibration produced upon closing/opening of the door of a microwave oven may result in gaps in the door around the window. These gaps may be no visible to the user; however, the microwave produces by the microwave oven will leak out of the microwave oven through these gaps. When one approaches the microwave oven during cooking, the leaked microwave will cause injury to the body of the person approaching the microwave oven.
Therefore, it is desirable to provide a measure that eliminates the aforesaid problems.